Performance Problem / javax.xml.xpath vs. org.apache.xpath

[Konrad Lanz <Ko...@iaik.tugraz.at>]

Hi Xalan Developers,

when using the javax.xml.xpath API there seems to be a big performance
hit compared to using the org.apache.xpath API.

When evaluating a compiled XPath expression multiple times on different
context nodes as specified in Xpath Filtering
http://www.w3.org/TR/xmldsig-core/#sec-XPath it seems to take about 30
times longer.


> e.g.:
> private XPathExpression compiledXPathExpr_;
> ...
> return ((Boolean) compiledXPathExpr_.evaluate(contextNode,
> XPathConstants.BOOLEAN)).booleanValue();


As a potential source for the performance hit we identified the Method
"private XObject eval ( Object contextItem )" in
"org.apache.xpath.jaxp.XPathExpressionImpl.eval()" .

It performs much worse compared to the following code ...

> e.g.:
> private XPath xpath_;
> ...
> XObject xobject = xpath_.execute(context_, contextNode,
>   prefixResolver_);
> boolean result = xobject.bool(); 
> return result;


We beleieve the time is lost on XPathContext creation.

Thanks in advance and best regards

Konrad Lanz


-- 
Konrad Lanz, IAIK/SIC - Graz University of Technology
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